JavaSwingJPanel放在另一个面板后面，而不是替换它

我正在做一个需要日历的项目；是的，我正在从头开始制作日历：

我已经把日历部分都设置好了，现在我正在处理上个月和下个月的按钮。现在，我正在实施前一个月，当我点击按钮时，前一个月确实会显示，但是它会显示在当前月份之后，而不是像您所想的那样替换它。起初，我没有看到它发生任何变化，所以我查看了我的代码，然后再次运行它。这一次，让窗户更大；就在那时，我看到前一个月落后于本月

这是我的全部代码。我做错了什么

import java.awt.Color;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.Month;

import javax.swing.*;

public class CalendarTest extends JFrame {
    private JPanel calPanel;

    CalendarTest() {
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        InitCal(LocalDate.now().getMonth(), LocalDate.now().getYear());

        this.pack();
        this.setVisible(true);
        this.setLocationRelativeTo(null);

    }

    private void InitCal(Month month, int year) {
        LocalDate date = LocalDate.of(year, ConvertMonthToInt(month), 1);
        DayOfWeek dayOfWeek;
        int dayOfMonth;

        GridBagConstraints c = new GridBagConstraints();
        calPanel = new JPanel(new GridBagLayout());

        c.gridx = 0;
        c.gridy = 0;
        c.fill = GridBagConstraints.BOTH;

        JButton previous = new JButton("<");
        previous.setBorderPainted(false);
        previous.setFocusPainted(false);
        previous.setBackground(Color.WHITE);
        previous.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent arg0) {
                // TODO Auto-generated method stub
                LocalDate prevDate = date.minusMonths(1);
                InitCal(prevDate.getMonth(), prevDate.getYear());
            }

        });
        calPanel.add(previous, c);

        c.gridx++;
        c.gridwidth = 3;
        calPanel.add(new JButton(month.toString()), c);

        c.gridwidth = 2;
        c.gridx += 3;
        calPanel.add(new JButton(Integer.toString(year)), c);

        c.gridwidth = 1;
        c.gridx += 2;
        calPanel.add(new JButton(">"), c);

        c.gridx = 0;
        c.gridy++;

        JLabel sunday = new JLabel("Sun");
        sunday.setHorizontalAlignment(JLabel.CENTER);
        calPanel.add(sunday, c);

        c.gridx++;
        JLabel monday = new JLabel("Mon");
        monday.setHorizontalAlignment(JLabel.CENTER);
        calPanel.add(monday, c);

        c.gridx++;
        JLabel tuesday = new JLabel("Tue");
        tuesday.setHorizontalAlignment(JLabel.CENTER);
        calPanel.add(tuesday, c);

        c.gridx++;
        JLabel wednesday = new JLabel("Wed");
        wednesday.setHorizontalAlignment(JLabel.CENTER);
        calPanel.add(wednesday, c);

        c.gridx++;
        JLabel thursday = new JLabel("Thu");
        thursday.setHorizontalAlignment(JLabel.CENTER);
        calPanel.add(thursday, c);

        c.gridx++;
        JLabel friday = new JLabel("Fri");
        friday.setHorizontalAlignment(JLabel.CENTER);
        calPanel.add(friday, c);

        c.gridx++;
        JLabel saturday = new JLabel("Sat");
        saturday.setHorizontalAlignment(JLabel.CENTER);
        calPanel.add(saturday, c);

        c.gridx = 0;
        c.gridy++;

        int fillBeginning = ConvertDayOfWeekToInt(date.getDayOfWeek());
        int count = fillBeginning;

        if (fillBeginning > 0) {
            LocalDate prev = date.minusMonths(1);
            int prevDays = GetDaysInMonth(ConvertMonthToInt(prev.getMonth()), prev.getYear());
            prevDays -= (fillBeginning - 1);

            while (fillBeginning > 0) {
                JButton b = new JButton(Integer.toString(prevDays));
                b.setBorderPainted(false);
                b.setFocusPainted(false);
                b.setBackground(new Color(100,150,200));
                calPanel.add(b, c);
                c.gridx++;
                fillBeginning--;
                prevDays++;
            }
        }

        int day = 1;
        int daysInMonth = GetDaysInMonth(ConvertMonthToInt(month), year);

        while(day <= daysInMonth) {
            if (count >= 7) {
                c.gridy++;
                c.gridx = 0;
                count = 0;
            }

            JButton b = new JButton(Integer.toString(day));
            b.setBorderPainted(false);
            b.setFocusPainted(false);
            b.setBackground(Color.WHITE);
            calPanel.add(b, c);
            count++;
            day++;
            c.gridx++;
        }

        int nextDays = 1;

        while (7 - count > 0) {
            JButton b = new JButton(Integer.toString(nextDays));
            b.setBorderPainted(false);
            b.setFocusPainted(false);
            b.setBackground(new Color(100,150,200));
            calPanel.add(b, c);
            c.gridx++;
            count++;
            nextDays++;
        }

        this.add(calPanel);
    }

    private int ConvertMonthToInt(Month m) {
        switch(m.toString()) {
        case "JANUARY" : return 1;
        case "FEBRUARY" : return 2;
        case "MARCH" : return 3;
        case "APRIL" : return 4;
        case "MAY" : return 5;
        case "JUNE" : return 6;
        case "JULY" : return 7;
        case "AUGUST" : return 8;
        case "SEPTEMBER" : return 9;
        case "OCTOBER" : return 10;
        case "NOVEMBER" : return 11;
        case "DECEMBER" : return 12;
        default: return 0;
        }
    }

    private int ConvertDayOfWeekToInt(DayOfWeek dow) {
        switch(dow.toString()) {
        case "SUNDAY" : return 0;
        case "MONDAY" : return 1;
        case "TUESDAY" : return 2;
        case "WEDNESDAY" : return 3;
        case "THURSDAY" : return 4;
        case "FRIDAY" : return 5;
        case "SATURDAY" : return 6;
        default : return 0;
        }
    }

    private int GetDaysInMonth(int m, int y) {
        switch(m) {
        case 4 : case 6 : case 9 : case 11 : return 30;
        case 1 : case 3 : case 5 : case 7 : case 8 : case 10 : case 12 : return 31;
        case 2 :
            if (IsLeapYear(y)) {
                return 29;
            } else {
                return 28;
            }
        default : return 0;
        }
    }

    private boolean IsLeapYear(int y) {
        if (y % 4 == 0) {
            return true;
        } else if (y % 100 == 0) {
            return false;
        }

        return false;
    }

    public static void main(String[] args) {
        new CalendarTest();
    }
}

看看2018年12月在2019年1月底的表现如何？我希望一月消失，取而代之的是十二月。此图像是在单击“上一步”按钮后调整大小后显示的

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我还尝试过放置JPanel calPanel=newjpanelnewgridbagloayout；在InitCal方法的内部。那只是和以前一样的问题。有什么建议吗？

您需要从框架中删除上一个面板，如下所示：

个人月，整数年{ ifcalPanel！=null{ 本品为去甲肾上腺素； 这是重新验证； } ... 最后，在添加新的月份面板后，您需要重新验证框架，如下所示：

... 这个.addcalPanel； this.revalidate；//您需要重新验证组件以查看更改。 }

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哦，哇。这是一个简单的解决方案。就在您回答之前，我正在重新验证和重新喷漆，我还尝试删除calPanel中的所有组件，但是我没有尝试删除面板本身。事实上，我必须在验证后立即调用此.pack，否则由于某些原因，我顶部的按钮会非常小。如果答案是您想要的并解决了问题，请不要忘记将其作为答案批准。